engine-gst: Fix obscure test failure
engine-gst: Fix obscure test failure

Work-around https://bugzilla.gnome.org/show_bug.cgi?id=698997

GNOME/rygel,jku/rygel,jku/rygel,Tarnyko/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Tarnyko/rygel